Ultrafast high power lasers are now employed in electron accelerators to generate X-rays or to inject highly accelerated electrons for further applications. However, the current lasers used are inefficient, due to the high power needed to pump the gain medium using indirect pumping. Recently it has been suggested that TeV-GeV accelerations can be achieved using picosecond or subpicosecond lasers for low plasma density. This project will fabricate ytterbium-doped sesquoxides and orthosilicate ceramic hosts, which can be efficiently pumped by semiconductor lasers and can be doped to high concentrations to provide optimal pulse length and power. Commercial Applications and other Benefits as described by the awardeeIn addition to benefiting the DOE accelerator program, the ceramic lasers should have great commercial potential due to their ability to provide ultrashort pulses. They should find use in the laser cutting welding industry, for laser-ranging applications for defense and space applications, and for biomedical and materials research in general